Henoch-Schonlein nephritis.

Henoch-Schonlein purpura is a clinical syndrome characterized by the association of skin, joint, and gastrointestinal symptoms. Henoch-Schonlein purpura is characterized by wide-spread vasculitis. Although the clinical symptoms of this disease are characteristic, the diagnosis is not always easy to establish because other forms of systemic vasculitis - mainly the microscopic form of periarteritis nodosa - may mimic the disease. In addition, in contrast to systemic lupus erythematosus, there are no biological tests that can identify Henoch-Schonlein purpura with certainty. Immunofluorescence microscopic techniques have made an important contribution to both the diagnosis and the study of the pathogenesis of the disease, particularly since they have demonstrated the presence of IgA deposits in the glomeruli and in the vessel walls. These findings not only confirmed the immunologic nature of the pathologic lesions but also drew attention to the remarkable similarity between Henoch-Schonlein purpura nephritis and IgA nephropathy.